During recent years, pickup trucks have gained popularity as a form of family transportation as they are able to transport both passengers and cargo. If the truck is being used to carry cargo, truck bed liners are often installed to protect the metal surfaces of the truck bed from scratches and dents which may lead to rust and which affect the aesthetic appearance of the bed. Some liners, as disclosed in U.S. Pat. No. 4,162,098, protect only the floor of the truck bed; some, as disclosed in U.S. Pat. No. 4,245,863, protect only the side walls of the bed; and most protect the floor, the end wall, both side walls, and the tailgate. Various materials such as wood (U.S. Pat. No. 4,505,508), vinyl (U.S. Pat. No. 4,279,439), and plastic (U.S. Pat. No. 4,693,507), are used in the manufacture of truck bed liners, and some, such as those disclosed in U.S. Pat. Nos. 4,505,508, 4,893,862, 4,944,612 and 4,986,590, are multi-piece liners, while most have a unibody construction. The most common truck bed liner is made of a plastic material formed for a custom fit of various makes and models of pickup trucks.
In addition to protectively covering the interior of the truck cargo bed, many truck cargo bed liners also employ generally horizontal flanges which overlay the top rails of the vertical walls of the truck cargo bed. These protective flanges, which are usually extensions of the various upright surfaces of the liner, serve to prevent damage to the truck bed rails which take the form of chips, scratches or dents. This damage often occurs when, for example, heavy objects being lifted and placed into the truck are set on these rails and then tumbled into the cargo bed.
While functioning to help protect the truck bed rails from avoidable and excessive damage, existing truck bed liner flanges suffer from several serious shortcomings including scuffing of the truck and warpage. Although bed liners often improve the aesthetic appearance of a truck, there are occasions when removal of the cargo bed liner is desired or necessitated. On such occasions, vehicle owners often discover to their dismay that the flanges which overlay the top rails have actually scratched and scuffed the very surfaces for which the flanges were specifically designed to protect. This type of scuffing along the top rails is especially undesirable for a variety of reasons. While truck cargo beds are typically expected to be damaged through normal usage, and therefore some scuffing of the cargo bed interior by the liner is not overly devastating, unsightly damage to the top rails suggests the trucks have been subject to improper treatment and may translate to lower truck resale values. Furthermore, the fact that many persons perceive the top rails as being outside the cargo bed and not subject to damage from use makes scuffing along these top rails all the more noticeable. Moreover, the scuffing of the top rail makes the top rail more susceptible to corrosion which is readily visible by casual observers.
Because vibrations and other normal operating motions of the vehicle cause the liner to move relative to the cargo bed, undesirable scuffing of the top rail inevitably occurs each place where the liner flange contacts and rubs against the top rail. The presence of foreign particles at the contact points between the liner and the top rail only compounds the scuffing damage to the rail. Despite this fact, cargo bed liners which utilize horizontal flanges that overlay the top rail wherein substantially the entire width of the top rail is contacted by the flange are well known in the art. For instance, U.S. Pat. No. 4,906,040 discloses a liner flange flush with the top surface of the truck bed wall. This configuration subjects virtually the entire area of the top surface to scuffing. In addition to overlaying and being flush with the top rail, other liner flanges, for instance as shown overlaying a top rail of a cargo bed side wall in U.S. Pat. No. 5,046,775 and a top rail of a tailgate in U.S. Pat. No. 5,000,503, hook over the top rail and terminate with a downward projecting lip against the outer surface of the truck wall. These designs not only can scuff the entire top rail, but also scratch the vehicle's finish where the lip contacts the outer panels of the truck. This damage is even more noticeable and unacceptable than damage merely to the top rail.
Other models of liner flanges which overlay and protect the top rail exist that do not contact substantially all of the top rail. For example, U.S. Pat. No. 4,595,229 and 4,750,776 each disclose horizontal liner flanges which are generally spaced apart from the top rails which they protect. Each flange terminates in a downwardly extending lip which abuts the top rail. U.S. Pat. No. 4,047,749 discloses a horizontal liner flange, overlaying the inner portion of a truck bed top rail, which includes a recess of a height less than the thickness of the liner to receive double sided tape and which terminates with a downwardly extending lip contacting the top rail. While these liner flange designs reduce the contact areas between the top rail and the liner and thereby decrease the area susceptible to scuffing, they create a different problem as an undesirable side effect. These designs ensure that very deep scratches and scuffs, although in a more isolated location than some other flanges, will result in the top rail. This effect occurs because the portion of the top rail contacting the liner flange lip bears the entire load applied to the liner flange. A broader area of contact is lacking to aid in dissipating the loading forces applied and thereby lessen the severity of the scratches.
In addition to the shortcoming of causing scuffing, truck bed liner flanges also tend to warp over time. When first purchased and installed in cargo beds, most existing horizontal liner flanges fit neatly against the truck top rails and contribute to the sleek appearance of the vehicle. However, repeated exposure to the elements or hot weather frequently causes the flanges to eventually warp and become wavy or undulating, resulting in relatively large gaps or spaces appearing between the liner flanges and the top rails of the vehicle. Besides detracting from the overall appearance of the vehicle, these gaps also allow more contaminants such as dirt or salt to enter between the truck bed liner and cargo bed, thereby increasing the likelihood of both scuffing damage and corrosion occurring in the truck cargo bed.